Process for regenerating catalyst particles

ABSTRACT

A process for regenerating catalyst particles is disclosed. The process includes the steps: (a) withdrawing a regeneration zone effluent comprising halogen from a regeneration zone, wherein the regeneration zone contains catalyst particles comprising halogen; (b) contacting a first portion of the regeneration zone effluent with adsorbent in a first adsorption zone, removing halogen from the first portion of the regeneration zone effluent, and withdrawing from the first adsorption zone a first adsorption zone effluent; (c) contacting the first adsorption zone effluent with a water removing material to create a first water-depleted stream; and (d) passing the first water-depleted stream to the regeneration zone. Other embodiments include different orders of the steps.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Division of copending application Ser. No.14/869,235 filed Sep. 29, 2015 which application claims benefit of U.S.Provisional Application No. 62/093,506 filed Dec. 18, 2014, the contentsof which cited applications are hereby incorporated by reference intheir entirety.

BACKGROUND OF THE INVENTION

The disclosure relates to a process for regenerating catalyst particleswherein a water removing material is used to remove moisture from one ormore process streams.

Numerous hydrocarbon conversion processes are widely used to alter thestructure or properties of hydrocarbon streams. Such processes includeisomerization from straight chain paraffinic or olefinic hydrocarbons tomore highly branched hydrocarbons, dehydrogenation for producingolefinic or aromatic compounds, reforming to produce aromatics and motorfuels, alkylation to produce commodity chemicals and motor fuels,transalkylation, and others.

Many such processes use catalysts to promote hydrocarbon conversionreactions. These catalysts tend to deactivate for a variety of reasons,including the deposition of coke upon the catalyst, and/or loss ofcatalytic metal promoters such as halogens. Consequently, thesecatalysts are typically reactivated in a process called regeneration.Regeneration can include, among other things, removing coke from thecatalyst by burning (combustion), and replenishing catalytic promoterssuch as halogens on the catalyst, and drying the catalyst.

One of the problems during regeneration of halogen-containing catalystsis the loss of halogen from the catalyst. This happens when catalystparticles are contacted with gases that, while regenerating the catalystparticles, tend also to remove halogen from the catalyst particles.Therefore, processes have been developed for returning a halogen tocatalyst particles undergoing regeneration. For example, U.S. Pat. No.6,881,391 discloses a method for regenerating catalyst particles whereinchlorine-containing vent gas from a catalyst regenerator is sent to anadsorption/desorption system to recover the chlorine, and the recoveredchlorine is passed back to the catalyst regenerator.

Water can build up in the circulating gas, and if using a catalystsensitive to moisture, then moisture reduction becomes desirable.

Therefore, what is needed is an improved process for the regeneration ofhalogen-containing catalysts wherein excess moisture can be removed fromthe process streams of the catalyst regeneration system.

SUMMARY OF THE INVENTION

The foregoing needs are met by a process for regenerating catalystparticles according to the invention.

It is an advantage of the invention to provide a catalyst regenerationsystem including a water removing material, such as a membrane, whereinwater can be selectively rejected from the regeneration vent gas thatleaves the regeneration zone and enters the burn zone. The membrane isvery stable in the highly acidic environment and highly selective toreacting with and removing water. The HCl, Cl₂ and all other moleculesare retained and can be sent to an adsorption/desorption system forrecovery of chlorine. The process is improved by sending a dry gas tothe adsorption zone. This reduces the build up of moisture in the burnzone of the catalyst regenerator of the regeneration zone. Other waterremoving materials may be used, and other forms of the materials may beused such as beads.

It is another advantage of the invention to provide a catalystregeneration system including a water-removing material that dries thereduction gas that is used in the reduction zone of the system. Reducingthe moisture in the reduction gas improves the reduction of the catalystand leads to improved yields.

These and other features, aspects, and advantages of the presentinvention will become better understood upon consideration of thefollowing detailed description, drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a catalyst regeneration system including a stackedarrangement of reactors, a regenerator, and an adsorption zone forremoving halogens from the regenerator vent gas and returning thesehalogens to the regenerator.

FIG. 2 illustrates the adsorption zone of FIG. 1.

FIG. 3 is a cross-sectional view of one water removing zone of thearrangement of FIG. 1 taken along line 3-3 of FIG. 1.

FIG. 4 is a cross-sectional view of the water removing zone of FIG. 3taken along line 4-4 of FIG. 3.

Like reference numerals will be used to refer to like parts from Figureto Figure in the following description of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a catalyst regeneration system 8 including a stackedarrangement of reactors, a regenerator in the regeneration zone, and anadsorption zone for removing halogens from the regenerator vent gas andreturning these halogens to the regenerator. It is understood that theadsorption zone may be operated in a desorption mode as well, such asfor desorbing adsorbed components. Line 10 supplies catalyst particlesto a valve 12. Hydrogen enters valve 12 through line 14 at a rate thatregulates the transfer of catalyst particles through valve 12 into line18. As catalyst particles enter line 18, more hydrogen enters the bottomof line 18 through line 16 and transports the catalyst particlesupwardly through line 18 to the top 20 of stacked reactor arrangement22, which the particles and lift fluid enter.

Catalyst particles flow from the top to the bottom of the stackedreactor arrangement 22. At the top 20, the catalyst particles pass firstthrough a reduction zone, where hydrogen gas reduces the metal on thecatalyst particles. From there the catalyst particles pass throughmultiple reactors where hydrocarbons contact the catalyst particles andcoke is deposited on the catalyst particles. The stacked reactorarrangement 22 permits continuous or intermittent flow of the catalystparticles from the top 20 to lower retention chamber 24 at the bottom.Additional hydrogen enters chamber 24 through a line (not shown) at arate that purges hydrocarbons from the catalyst particles in chamber 24.

Catalyst particles containing coke deposits flow from chamber 24 andthrough line 26. In line 26, hydrogen and hydrocarbons are displacedfrom the catalyst particles to prevent any carry-over of hydrogen andhydrocarbons to regenerator 40. At the bottom of line 26, a valve 28transfers catalyst particles upwardly through line 34. Nitrogen entersvalve 28 through line 30 and additional nitrogen enters the bottom ofline 34 through line 32.

Catalyst particles pass through line 34 into disengager 36. Nitrogenenters disengager 36 through a line (not shown) at a rate that separatesbroken or chipped catalyst particles and catalyst fines from the wholecatalyst particles. The catalyst chips and fines exit through anotherline (not shown) for collection. The whole catalyst particles flow fromthe bottom of disengager 36 through lines 38 to regenerator 40.

Lines 38 discharge catalyst particles into conduits 42 insideregenerator 40. Conduits 42 feed the catalyst particles to annularregeneration zone 48 formed by outer catalyst particle retention screen46 and inner catalyst particle retention screen 52. Bed 48 is in a cokecombustion zone 50. In this embodiment, regenerator 40 is cylindrical inform, as are retention screens 46 and 52, which are concentric withregenerator 40. Screens 46 and 52 are perforated with holes that arelarge enough to allow gas to pass through bed 48 but do not permit thepassage of catalyst particles therethrough. Outer screen 46 extendsdownward from lines 42 and is supported at its bottom and its top tokeep it centered in regenerator 40. Inner screen 52 is attached to thetop head of regenerator 40 and extends downward from there to a pointslightly above the lower end of the screen 46. The bottom of innerscreen 52 is open to allow gas containing oxygen and chlorine to flowupward from cylindrical regeneration zone 58 to central section 54, aswill be described hereinafter.

The bottom of bed 48 is open to allow catalyst particles to empty frombed 48 into bed 58. The catalyst particles in bed 58 are located in achlorination zone 60. Bed 58 is defined in part by annular baffle 56.Catalyst particles flow from bed 58 into the open volume betweentruncated conical baffle 72 and conical baffle 68, which is concentricwith baffle 72. From there, the catalyst particles flow downwardly intoan annular holdup zone 76 defined by a lower cylindrical portion 74 ofbaffle 72 and a lower cylindrical portion of baffle 68. The annularvolume of catalyst particles retained between baffles 72 and 68 providesa gas seal to limit the flow of gases upwardly through the catalystparticles into bed 58. Catalyst particles flow from zone 76 intocylindrical regeneration zone 84. The catalyst particles in bed 84 arelocated in a drying zone 80. Bed 84 is defined in part by annular baffle79. The catalyst particles are periodically transferred from bed 84 bywithdrawing a predetermined volume of catalyst through line 102 which inturn allows the catalyst particles to slump downward through the packedcatalyst beds in disengager 36 and in zones 50, 60, and 80.

The catalyst particles exiting regenerator 40 through line 102 pass tonitrogen seal drum 104, through line 106, and to lock hopper arrangement108. Seal drum 104 and lock hopper arrangement 108 control the transferof catalyst particles back to stacked reactor arrangement 22. Thenitrogen seal drum 104 and lock hopper arrangement 108 also displaceoxygen gas from the catalyst particles to prevent any carry-over ofoxygen to stacked reactor arrangement 22.

Looking now to the gas flows, recycle gas enters the coke combustionzone 50 through line 100. The recycle gas is distributed in annularchamber 44 that extends around screen 46 and is defined by screen 46 andthe vessel wall of regenerator 40. An upper portion of screen 52 isimpermeable to gas flow, or blanked off, to prevent gas flow fromchamber 44 across the top of the regenerator 40. As the recycle gaspasses through regeneration zone 48, oxygen is consumed in thecombustion of coke and gas is collected in section 54. The process ofcombusting coke removes chloride from the catalyst particles, andtherefore the gas collected in section 54 contains not only water andcarbon dioxide but also chlorine and hydrogen chloride.

The gas that collects in section 54 includes not only gas from bed 48,but also gas containing oxygen, chlorine, and hydrogen chloride flowingupward from bed 58. Because the gas that collects in section 54 includesgas that will be vented from the coke combustion zone 50 as well as gasthat will be recycled in the coke combustion zone 50, the gas is usuallydenoted “vent gas/recycle gas”. The vent gas/recycle gas leaves section54 and passes through line 86. to cooler 88. Cooler 88 uses any suitablecooling medium such as water or air, and removes some of the heat fromthe vent gas/recycle gas during normal operation. The cooled ventgas/recycle gas flows through line 90 and splits into two portions. Oneportion is recycled to the coke combustion zone 50 and is called therecycle gas stream. This portion is conveyed by line 92 to blower 94 andthen passes through line 96 to heater 98. Heater 98 heats the recyclegas stream to carbon-burning temperatures during start-up and to alesser degree adds heat to the recycle gas stream during normaloperation. Heater 98 operates in conjunction with cooler 88 to regulatethe heat content of the recycle gas stream. The recycle gas streampasses through line 100 and enters coke combustion zone 50.

The other remaining portion of the cooled regeneration vent gas streamis called the regeneration vent gas and flows through line 110 to cooler114. Cooler 114 cools the regeneration vent gas stream by indirect heatexchange with any suitable cooling medium such as water or air. Thecooled regeneration vent gas flows through line 116 to pressureregulating valve 118. Pressure indicator-controller 112 measures thepressure in line 110 and generates signal 120. Signal 120 isrepresentative of the difference between the actual pressure and thedesired pressure in line 110. Signal 120 regulates the extent of openingof valve 118. The desired pressure in line 110 is set in order tomaintain a target pressure in one of the zones of the regenerator 40,usually the coke combustion zone 50. After being cooled and depressured,the regeneration vent gas stream is at the desired gas inlet temperaturefor adsorption and flows through line 122 to adsorption zone 123.

A better understanding of adsorption zone 123 can be obtained from FIG.2. Zone 123 comprises two beds 150 and 152 and the other lines, thevalves, and the other equipment shown in FIG. 2. Beds 150 and 152contain an adsorbent such as alumina. When bed 150 operates inadsorption mode, bed 152 operates in desorption mode. The regenerationvent gas stream in line 122 flows through line 124, valve 128, line 132,and line 146, and enters bed 150. The adsorbent in bed 150 adsorbs atleast some of the chlorine and hydrogen chloride from the vent gas. Theadsorption effluent gas flows through line 154, valve 158, and line 162,and the effluent is discharged from zone 123 through line 166. Ifdesired, this effluent can be sent to conventional facilities (notshown) to neutralize any residual chlorine or hydrogen chloride that maybe present in the effluent. However, the residual chlorine and hydrogenchloride content is so relatively low that the need for such anadditional neutralization step is often eliminated.

Looking at FIG. 1, line 232 supplies makeup air to coke combustion zone50. This makeup air is introduced, however, initially to drying zone 80,from which most of the oxygen in the makeup air ultimately makes its wayto coke combustion zone 50. Air from line 232 is added to regenerator 40at a rate of addition generally equal to the rate of vent gas in line110. Air in line 232 is dried in drier 234 and then passes through line236 to heater 238, which raises the temperature of the air stream toabout 566° C. (1050° F.). The heated, dry air stream passes through line240 to drying zone 80. The air stream enters annular space 82, which isdefined by annular baffle 79 and the vessel wall of regenerator 40.Annular baffle 79 is used to uniformly distribute the air through bed84. Contacting the catalyst in bed 84 with the heated, dry air removeswater from the catalyst.

Drying bed effluent gas, which is mostly air now laden with water, exitsthe top of bed 84. Pressure drop provided by zone 76 forces the majorityof the upward flowing gas into annular space 78, which is defined by thevessel wall of regenerator 40, baffles 72 and 74, and partition 70. Mostof the water-laden effluent gas flows through line 168 to zone 123 to beused for desorption. Referring to FIG. 2, the gas in line 168 flowsthrough line 170, line 192, valve 196, and line 200, and enters bed 152.The adsorbent in bed 152 contains chloride, which is desorbed and exitsas hydrogen chloride and chlorine with the effluent of bed 152. Aportion of the gas flowing through line 200 may be made to bypass bed152 through a bypass line (not shown). Bed 152 effluent flows throughline 204, line 208, valve 212, line 216, line 218, and line 226 toheater 228 (see FIG. 1). Heater 228 heats the gas to the desired gasinlet temperature, and the gas flows through line 230 and enterschlorination zone 60. Flow indicator 220 measures the flow rate of theeffluent in line 218, and analyzer 222 measures the concentrations ofchlorine and hydrogen chloride in the effluent in line 218. Thesemeasurements of flow rate and concentrations allow computation of thequantities of chlorine and hydrogen chloride per unit time carried bythe bed 152 effluent to chlorination zone 60. If the rate of chlorine orhydrogen chloride is too low for the requirements of the chlorinationzone 60, additional chlorine-containing materials such as a chlorinatedparaffin can be added to line 218 through line 224.

The gas that contacts the catalyst in bed 58 comprises a mixture of gasflowing through line 230 and gas flowing upward from annular space 78.This mixture is formed in a two-pass baffle system 69 before enteringthe bottom of bed 58. Partition 70 is a flat plate, which may be solidand impermeable to gas flow or alternatively may define a plurality ofrestriction orifices that allow gas to flow through partition 70. Whenpresent, the restriction orifices are sized to produce a pressure dropfor flow passing through partition 70. The pressure drop induces most ofthe gas flow from space 78 to flow through zone 123 and to enter space62 via line 230. When the restriction orifices are not present,partition 70 functions as a barrier to gas flow, forcing even more ofthe gas flow out to zone 123. If needed, a compressor or blower (notshown) can be placed anywhere in line 168, zone 123, line 218, or line226 to force this gas flow through zone 123. When the restrictionorifices are present, the remainder of the gas flow from space 78 entersspace 62 through partition 70. If the pressure drop is suitable, thepreviously mentioned chlorine-containing materials added into line 218through line 224 may instead be introduced directly into space 62. Space62 is defined by upper cylindrical portion 66 of baffle 72, partition70, baffle 56, and the vessel wall of regenerator 40. Cylindricalportion 66 is concentric with annular baffle 56. From space 62 themixture of gases flows into space 64 defined by cylindrical portion 66and annular baffle 56. From space 64, the gases enter the bottom of bed58.

Prior to being placed in adsorption mode, bed 150 operated in desorptionmode. While bed 150 was in desorption mode, the chloride on theadsorbent was desorbed and passed to chlorination zone 60 through line218. This desorption depleted the adsorbent in bed 150 of chloride, andthereby prepared the adsorbent in bed 150 for use in adsorption mode.FIG. 2 provides an understanding of how bed 150 operated in desorptionmode. The gas in line 168 flowed through line 190, valve 194, and line198, and entered bed 150. The adsorbent in bed 150 contained chloride,which was desorbed and exited with the effluent of bed 150. Bed 150effluent flowed through line 202, line 206, valve 210, and line 214, andinto line 218.

Conversely, prior to being placed in desorption mode bed 152 operated inadsorption mode. While bed 152 was in adsorption mode, the chlorine andhydrogen chloride from the vent gas stream were adsorbed on theadsorbent. This adsorption added chloride to the adsorbent in bed 152,and thereby prepared the adsorbent in bed 152 for use in desorptionmode. When bed 152 was in adsorption mode, the vent gas stream in line122 flowed through line 126, valve 130, line 134, and line 148, andentered bed 152. The adsorbent in bed 152 adsorbed some of the chlorineand hydrogen chloride from the vent gas. The adsorption effluent gasflowed through line 156, valve 160, and line 164, before beingdischarged through line 166.

If the pressure used for removing halogen from the vent gas stream isless than the pressure used for removing halogen from the adsorbent,then a bed that has been used for removing halogen from the vent gasstream should be pressured up to prior to removing halogen from the bed.A convenient gas source for this pressuring step is the gas that isbeing used for removing halogen from the bed. In the case of pressuringbed 152, valve 184 is opened so that this gas may flow from line 168,through lines 170 and 172, through restriction orifice 174, throughlines 176 and 180, through valve 184, through lines 188 and 204, andinto bed 152. In the case of pressuring bed 150, valve 182 is opened sothat the gas flows from line 168, through lines 170 and 172, throughorifice 174, through lines 176 and 178, through valve 182, through lines186 and 202, and into bed 150. Orifice 174 is sized to set a gas flowrate corresponding to a desired pressuring rate.

After halogen has been removed from an adsorbent bed, and if thepressure used for removing halogen from the vent gas stream is less thanthe pressure for removing halogen from the adsorbent bed, that adsorbentbed should be depressured prior to being placed in adsorption mode. Aconvenient destination for the gas released during depressuring is a bedthat is being used for adsorption, since the released gas may containhalogen. In the case of depressuring bed 150, valve 140 is opened sothat gas flows from bed 150, through lines 146 and 136, through valve140, through line 144, through restriction orifice 142, through lines138 and 148, and into bed 152. In the case of depressuring bed 152,valve 140 is opened so that gas flows from bed 152, through lines 148and 138, through orifice 142, through line 144, through valve 140,through lines 136 and 146, and into bed 150. Orifice 142 is sized to seta gas flow rate corresponding to a desired depressuring rate.

Halogen recovery is generally greater than about 80 wt-% and preferablygreater than about 90 wt-%. The vent gas stream that enters the bedbeing used for adsorption typically contains from 50 to 10000 mol-ppmhydrogen chloride and from 1 to 500 mol-ppm chlorine. The vent gasstream enters cooler 114 at typical catalyst regeneration temperaturesof from about 371° C. to about 538° C. (700° F. to 1000° F.). Most ofthe cooling occurs in cooler 114 but some additional cooling may occuras a result of depressuring the vent gas stream across valve 118. Theinlet temperature of the gas entering a bed in adsorption mode istypically at from about 149° C. to about 260° C. (300° F. to 500° F.).If the temperature of the adsorbent in a bed that is placed inadsorption mode is initially different from the inlet temperature of thegas, the adsorbent temperature will rise or fall. Therefore, after someperiod of contacting the temperature at which adsorption occurs willusually be within the range of from about 149° C. to about 260° C. (300°F. to 500° F.).

The regeneration zone and the adsorption zone may be in immediateproximity to one another, or the regeneration zone and the adsorptionzone may be spaced apart from one another. The distance between theregeneration zone and adsorption zone may require conduits to conductstreams between the two zones and the two zones may be spaced apart by adistance of from 20 meters to 1000 meters or more. By the term “spacedapart,” it is intended that the adsorption zone be a separate structurefrom the regeneration zone that is separated from the regeneration zoneby a distance, except for connecting lines such as the regeneration ventgas line or other lines. In an example process, the regeneration zone isdisposed within a regeneration zone vessel, and the adsorption zone isdisposed within an adsorption vessel that is separate from the vessel ofthe regeneration zone. The adsorption vessel can include, for example, aseparate stack of modules that are shop fabricated. This allows improvedquality control, and reduces or eliminates modification to existingequipment such as the regeneration zone.

Turning now to FIGS. 1, 3 and 4, the catalyst regeneration system 8includes moisture removal zones 310, 320, 330, 340, and 350. Themoisture removal zone 310 is located in line 96 in order to remove waterfrom the recycle gas stream that is fed back into the coke combustionzone 50. The moisture removal zone 320 is located in line 122 in orderto remove water from the vent gas stream that is fed into theadsorption/desorption zone 123. The moisture removal zone 330 is locatedin line 218 in order to remove water from the stream from theadsorption/desorption zone 123 that is fed back into the chlorinationzone 60. The moisture removal zone 340 is located in line 232 in orderto remove water from the makeup air that is supplied to the cokecombustion zone 50. The moisture removal zone 350 is located in line 16in order to remove water from the hydrogen that enters the reductionzone of the stacked reactor arrangement 22.

Referring now to FIGS. 3 and 4, the moisture removal zone 320 is shownin greater detail. The moisture removal zone 320 includes a housingformed by opposed spaced apart transverse walls 410 and 411 that extendbetween a cylindrical outer wall 412. Cylindrical tubes 326 extendbetween the walls 410 and 411. The tubes 326 each include a hollowinterior space 327 defined by an inner surface 328. The tubes 326 alsoinclude an outer surface 329. Any number of tubes 326 can be arrangedbetween the walls 410 and 411. Process fluid F from line 122 flowsthrough the interior space 327 of each tube 326 as shown in FIG. 4.

The wall 325 of each of the cylindrical tubes 326 comprises a materialthat is selectively permeable to water. In one non-limiting example, thematerial of the walls 325 of each of the cylindrical tubes 326 removesgases based on their chemical affinity for sulfonic acid groups.Sulfonic acid groups have a very high affinity for water, so sulfonicacid groups absorb water from the process fluid F into the wall materialat the inner surface 328 of each wall 325. Once absorbed into the wall325, the water permeates from the inner surface 327, one sulfonic groupto another until the water reaches the outside surface 329 of the tubes326, where it evaporates into the surrounding gas in the housing formedby the transverse walls 410 and 411 and the cylindrical outer wall 412.

If the gases inside the tubes 326 contain more water (have a higherwater vapor pressure) than the gases outside the tubes 326, the watervapor will move out of the tubes 326. If the gases outside of the tubes326 contain more water, water vapor will move in. Therefore, a hot drypurge gas flow P (see FIG. 4) is moved over the tubes 326 to removewater from the interior space of the housing. The dry purge gas flow Pis a heated, dry air stream from heater 238 that passes through lines306, 308 and into line 322. After passing through the interior space ofthe housing and removing water, the purge gas is vented through line323. Suitable valves may be provided in lines 322 and 323 to controlpurge gas pressure levels.

In one non-limiting example embodiment, the water removing material ofthe walls 325 of each of the cylindrical tubes 326 comprises a polymericbackbone with sulfonic acid groups. Preferably, the water removingmaterial comprises a fluorocarbon having sulfonic acid groups. Mostpreferably, the water removing material comprisestetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acidcopolymer, which is sold under the trademark Nafion®. The water removingmaterial of the walls 325 of each of the cylindrical tubes 326 acts as asemi-permeable membrane that allows water molecules to pass through thematerial but other molecules are retained in the process fluid stream inline 122.

The other moisture removal zones 310, 330, 340, and 350 can be of asimilar construction to the moisture removal zone 320 and therefore, themoisture removal zones 310, 330, 340, and 350 will not be described infurther detail. Looking at FIG. 1, the moisture removal zone 310receives dry purge gas flow P as a heated, dry air stream from heater238 that passes through lines 306, 308 and into line 312. After passingthrough the interior space of the housing of the moisture removal zone310, the purge gas is vented through line 313. Likewise, the moistureremoval zone 330 receives dry purge gas flow P as a heated, dry airstream from heater 238 that passes through lines 306, 308 and into line332. After passing through the interior space of the housing of themoisture removal zone 330, the purge gas is vented through line 333.Likewise, the moisture removal zone 340 receives dry purge gas flow P asa heated, dry air stream from heater 238 that passes through line 306and into line 342. After passing through the interior space of thehousing of the moisture removal zone 340, the purge gas is ventedthrough line 343. Likewise, the moisture removal zone 350 receives drypurge gas flow P as a heated, dry air stream from heater 238 that passesthrough line 306 and into line 352. After passing through the interiorspace of the housing of the moisture removal zone 350, the purge gas isvented through line 353.

Reducing the moisture in the process flow streams of the catalystregeneration system 8 using any combination of one, two, three, four, orfive of the moisture removal zones 310, 320, 330, 340, 350 improves thereduction of the catalyst and reduces the build up of moisture in theburn zone of the catalyst regenerator, thereby improving yields.

In another embodiment, the material that is selectively permeable towater may be used in form of beads. For example, the water removingmaterial that comprisestetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acidcopolymer, which is sold under the trademark Nafion® may be in the formof beads. The beads may be housed in one or more vessels, and in oneembodiment the beads are housed into dual vessels with one vessel inactive drying mode while the other vessel is being regenerated. When thewater uptake capacity of the beads in the vessel in active drying modehas been reached, or before capacity has been reached, the vessel isswitched to the regeneration mode, and the vessel that had been inregeneration mode is switched to active drying mode. The beads may beregenerated by drying with a hot dry gas stream such as hot dry air orhot dry nitrogen. For regeneration, the hot drying gas may be passedover the beads in an up-flow or in a down-flow mode. Regenerant may beflushed from the vessel before being placed in service. An advantage ofthis embodiment is a continuous dry stream recycled to the continuouscatalyst regeneration system without significant swings in flow rate.The moisture removal zones having moisture removal material in bead formmay be located in any of the locations described above. Combinations ofmoisture removal zones in membrane form, bead form, and tubular form maybe employed. It is also envisioned that a moisture removal zone may belocated prior to the adsorption zone.

Although the invention has been described in considerable detail withreference to certain embodiments, one skilled in the art will appreciatethat the present invention can be practiced by other than the describedembodiments, which have been presented for purposes of illustration andnot of limitation. Therefore, the scope of the appended claims shouldnot be limited to the description of the embodiments contained herein.

1. A process for regenerating catalyst particles, the processcomprising: withdrawing a regeneration zone effluent comprising halogenfrom a regeneration zone, wherein the regeneration zone comprisescatalyst particles comprising halogen; contacting a first portion of theregeneration zone effluent with a water removing material to create afirst water-depleted stream; contacting the first water-depleted streamwith adsorbent in an adsorption zone, removing halogen from the firstwater-depleted stream, and withdrawing from the adsorption zone anadsorption zone effluent; and passing at least a portion of theadsorption zone effluent to the regeneration zone.
 2. A process foradsorbing hydrogen chloride (HCl) from a regeneration vent gas, theprocess comprising: cooling the regeneration vent gas from aregeneration zone; passing the cooled regeneration vent gas to anadsorption zone that is spaced apart from the regeneration zone;adsorbing HCl from the regeneration vent gas onto a spent catalyst inthe adsorption zone to enrich the spent catalyst with HCl to provideHCl-rich catalyst and deplete HCl from the regeneration vent gas toprovide HCl-lean regeneration vent gas; purging the HCl-leanregeneration vent gas as an effluent gas; removing water from theregeneration vent gas or the HCl-lean regeneration vent gas bycontacting with a water removing material; and passing the HCl-richcatalyst to the regeneration zone.
 3. The process of claim 2 wherein thewater removing material is within the adsorption zone.
 4. The process ofclaim 2 wherein the water removing material comprises a membraneselectively permeable to water.
 5. The process of claim 2 wherein feedflow of the first portion of the regeneration zone effluent istangential to a surface of the water removing material.
 6. The processof claim 2 wherein the water removing material comprises a fluorocarbonhaving sulfonic acid groups.
 7. The process of claim 2 wherein the waterremoving material comprisestetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acidcopolymer.
 8. The process of claim 2 wherein the water removing materialis in a membrane form, a tubular form, or a bead form.
 9. A process forregenerating catalyst particles, the process comprising: (a) withdrawinga regeneration zone effluent comprising halogen from a regenerationzone, wherein the regeneration zone contains catalyst particlescomprising halogen; (b) contacting a first portion of the regenerationzone effluent with a water removing material to create a firstwater-depleted stream; and (c) passing the first water-depleted streamto the regeneration zone, and at least partially regenerating at least aportion of the catalyst particles in the regeneration zone and removingat least a portion of the halogen from the catalyst particles in theregeneration zone.
 10. The process of claim 9 further comprising: (d)contacting a second portion of the regeneration zone effluent withadsorbent in an adsorption zone, removing halogen from the secondportion of the regeneration zone effluent, and withdrawing from theadsorption zone an adsorption zone effluent; and (e) passing at least aportion of the adsorption zone effluent comprising halogen to theregeneration zone.
 11. The process of claim 10 wherein step (d)comprises: contacting the second portion of the regeneration zoneeffluent with a second water removing material to create a secondwater-depleted stream; and contacting the second water-depleted streamwith adsorbent in the adsorption zone.
 12. The process of claim 10wherein step (e) comprises: contacting the adsorption zone effluent witha second water removing material to create a second water-depletedstream; and passing the second water-depleted stream to the regenerationzone.